1. Field of the Invention
This invention relates to door closer assemblies and more particularly to a door closer wherein means are provided for rendering ineffective the main closer spring while maintaining the door under hydraulic control of the hydraulic circuit located in the door closer.
2. Description of the Prior Art
Known door closers utilize latching means to latch a closure member to prevent closure thereof by a main spring or the equivalent. When the latch is released, the closure closes under the force of the actuating means, which in most cases is a spring. An example of this type of operation is disclosed in the Bouton U.S. Pat. No. 1,888,712 which discloses a latch 34 which, when released by a solenoid 35, allows a gate to close under the force of an actuator. The Kaiser U.S. Pat. No. 767,346 also discloses a similar operation wherein a curtain is closed upon release of a counterbalance 17. Other art which discloses a similar type of operation include the Nole U.S. Pat. No. 944,494; the Schloss U.S. Pat. No. 1,430,192; and the Puhl U.S. Pat. No. 1,243,101. In all of the above cited patents, the closure member is not operable to be manually moved when the latch is actuated. The Peterson U.S. Pat. No. 4,010,572 discloses the use of a pneumatic cylinder for counteracting the force of the spring. However, in Peterson the counterbalancing of the spring by the pneumatic means only occurs at one point in the cycle of the closure. During the remainder of the cycle the spring will be effective to bias the door. Peterson does not disclose rendering the spring ineffective but rather discloses counterbalancing the spring force.